Traditionally, absorbent products such as panty liners, sanitary napkins and incontinence pads have been held in place by pressure sensitive adhesive, typically a double sided tape or a hot melt type glue, disposed on the garment facing side of the pad. The pressure sensitive adhesive holds the pad in place by adhering it to the crotch of the wearer's undergarment. The pressure sensitive adhesive is covered with release paper that protect the adhesive from dirt and unintended adhesion during manufacture, packaging and storage. Typically, the release paper has been coated on one side with a coating, which may be silicone, that reduces the adherency to the adhesive of the coated side of the release paper.
Since the release paper must be removed by the user just prior to application of the product to an undergarment, its presence creates waste and complicates the utilization of the product. One approach for dispensing with the release paper, disclosed in U.S. Pat. No. 4,475,913 (Hlaban), involves folding an absorbent batt along its longitudinal edges so as to create soft edges for the product. In so doing, a centrally disposed cavity is formed that extends the length of the product. A baffle, supplied in fluid form, is then extruded into the cavity so as to conform to it and a pressure sensitive adhesive is deposited onto the portion of the baffle within the cavity. According to this reference, no release paper is need because the adhesive is shielded by the walls of the cavity.
Unfortunately, this approach suffers from a variety of drawbacks. First, the manufacturing process is complex--the edges must be folded and maintained in place during extrusion of the baffle, the amount of film extruded must be carefully controlled, and the cavity shape must be maintained in the extruded film. Second, the folding creates a thick, bulky product, whereas many users prefer a thin, less obtrusive product. Third, the cavity will generally be relatively deep, since its walls are substantially the thickness of the absorbent batt. Such depth will make it difficult for a user to bring the adhesive into contact with the under-garment unless the cavity is relatively wide, in which case the adhesive will not be adequately protected from unintended contact. Lastly, this approach limits the location of the adhesive to the longitudinal center of the product, whereas locating the adhesive around the garment facing surface in a more dispersed pattern may create a more secure attachment.
Consequently, it would be desirable to provide a method of making an absorbent product having pressure sensitive positioning adhesive in which the adhesive was adequately protected from unintended contact prior to use without the need for release paper but that allowed the user to readily attach the product to an under-garment. Moreover, it would be desirable to provide a method of making such a product without creating undue complexity in the manufacturing process and in a manner that allowed the adhesive to be dispersed around the garment facing surface in a variety of patterns.